Brad Graevs paused his kayak at the edge of a boisterous spectacle: thousands of frenzied Western Grebes, breeding, feeding, and in the shallows of Lake Almanor. It was late July, the height of nesting season at the reservoir 160 miles north of Sacramento, California. The elegant birds slowly circled each other, heads bobbing, weeds dripping from their canary-colored bills. Graevs counted 1,184 active nests in total, a promising start to the season鈥攐r so he thought.
When Graevs returned to the reservoir on August 13, the entire colony had been abandoned. 鈥淚t was just over . . . nothing left,鈥 says the former grebe project manager for the .
The mystery didn鈥檛 take long to solve. In the days before the birds鈥 disappearance, the reservoir鈥檚 owner, the San Francisco-based utility Pacific Gas & Electric Co., sapped it to supply its hydroelectric power generators and downstream water users. This was after an agreement between Plumas 探花精选 and the company that outlined protocols for preserving the grebes鈥 nesting habitat. The chapter is now pairing up with to hopefully negotiate a new deal with PG&E officials.
Each summer, Western and Clark鈥檚 Grebes migrate from their wintering waters in the Pacific Ocean to the inland lakes of California. (Because they lose their flight muscles after migration, they鈥檙e committed to the sites they choose for the breeding season, making disturbances all the more impactful.) But as climate change and diversions cause the state鈥檚 natural formations to dry up, Almanor and other reservoirs have become increasingly critical for reproduction: They support more than 90 percent of the state鈥檚 breeding-grebe population and 45 percent of that in the Intermountain West. That has encouraged water managers to adapt their practices to protect bird colonies.
Take Thermalito Afterbay in Oroville, for example. In 2004, California Department of Water Resources managers began testing how deep the reservoir needed to be fulfill both the grebes鈥 needs and the state's hydroelectric and downstream-water obligations. They established a goal of fluctuating levels no more than five feet during the birds鈥 nesting season.
鈥淚t was essentially a good faith effort our department and management made voluntarily to protect this species,鈥 says Ryan Martin, senior environmental scientist with the Department of Water Resources.
Plumas 探花精选 would like to strike a similar perpetual deal with PG&E, which after a spate of fires. The chapter has been monitoring Almanor鈥檚 grebes since 2010, and has found a strong correlation between water levels and the birds鈥 reproductive success. If the reservoir鈥檚 surface drops too quickly, the eggs and chicks are left vulnerable to gulls, otters, and other predators. That鈥檚 what Lindsay Wood, executive director of Plumas 探花精选, suspects happened last year, resulting in the colony鈥檚 lowest success rate in nearly a decade. A similar sudden drawdown in 2016 led to 788 abandoned nests and a combined loss of 4,000 nestlings.
To secure a better future for grebes, Plumas 探花精选 members have been working with PG&E since 2013 to stabilize Almanor鈥檚 water levels. In 2016, they drew up a tentative agreement to cap drawdowns from July 1 to August 31. But a pilot project that summer demonstrated the complexity of PG&E鈥檚 water demands, so 探花精选 amended its recommendation to a maximum of 0.84 inches a day.
Then, last year, PG&E lowered the lake levels by as much as 1.92 inches a day, according to a letter written this January by Mike Lynes, 探花精选 California's policy director. The company鈥檚 officials dispute 探花精选's calculations: They state that the average drawdown rate between August 3 and August 13 was consistent with Plumas 探花精选鈥檚 revised recommendation. An email from Paul Moreno, the utility's marketing and communications officer, also attributed the 2018 nest failures to other elements such as strong winds, smoke, and reduced populations of the fish grebes feed on.
Still, Lynes and Wood are looking for a path forward before the birds return to Almanor in coming weeks. 鈥淲e're trying to figure out why this is happening and what we can do about it. It's a significant ecological problem,鈥 Lynes says.
A meeting scheduled for today with Janet Walther, PG&E鈥檚 hydroelectric relicensing compliance officer, could provide answers for both 探花精选 and wildlife authorities. The state鈥檚 is part of a $2.8 million project to restore natural resources damaged by oil spills near San Francisco. To offset , the California and U.S. Fish and Wildlife departments have put $774,000 into protecting nesting colonies at inland water bodies.
鈥淚f you're investing these dollars to get birds to breed and then every few years you're sucking all the water away and the population crashes, you're not doing a great job,鈥 Lynes says. What鈥檚 more, he adds, PG&E could face fines for the Almanor disturbance under and the federal Migratory Bird Treaty Act.
The Western Grebes at Almanor represent as much as 5 percent of the species鈥 global population, says Ryan Burnett, an ecologist with , a California-based research institution. After 19 years of observing colonies at Almanor and other lakes, he believes that nest abandonment due to drawdowns is more common than we think. That said, cases like the one with PG&E should be avoidable: 鈥淎ll the pieces are in place for local volunteers to monitor the nesting and work with the company to manage water levels consistently during that one-month period each year,鈥 Burnett says.
As summer approaches, the grebes are beginning their nocturnal migration from the ocean to the lakes. Wood is counting on another season of courtship at PG&E鈥檚 reservoir鈥攐ne that鈥檚 full of thousands of grebes nodding, bobbing, and eventually, ferrying around their chicks as a sure sign of breeding success.